Apparatus for generating electrical energy and method for manufacturing the same

ABSTRACT

Disclosed is an apparatus for generating electrical energy that includes; a first electrode, and a second electrode spaced apart from the first electrode, and an energy generation layer disposed between the first electrode and the second electrode, wherein the energy generation layer comprises a photoelectric conversion layer and a plurality of piezoelectric nanowires, and wherein when an external force is applied to at least one of the first electrode and the second electrode, the plurality of piezoelectric nanowires are transformed to generate electrical energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/862,919, filed on Aug. 25, 2010, which claims priority to KoreanPatent Application No. 10-2009-0078948, filed on Aug. 25, 2009, KoreanPatent No. 10-2009-0094374, filed on Oct. 5, 2009, and Korean Patent No.10-2010-0046629 filed on May 18, 2010, the contents of which in theirentirety are herein incorporated by reference.

BACKGROUND

1. Field

This disclosure relates to an apparatus for generating electricalenergy, and a method of manufacturing the apparatus for generatingelectrical energy.

2. Description of the Related Art

Recently, the advent of nanoscale devices has been enabled due to adecreasing in size, and an increase in performance, of electronicdevices. In order to manufacture the nanoscale devices, technologiessuch as nanowire formation have been developed. The term “nanowire” asused herein refers to an ultrafine wire having a cross-sectionaldiameter from about a few nm to about a few hundred nm. The length ofthe nanowire may be grown to tens to thousands of times, or more, of thediameter thereof.

The nanowire may exhibit different electrical, chemical, physical, andoptical characteristics from general characteristics of an existing bulkstructure. Increasingly integrated and intricate devices can be realizedusing molecular characteristics of nanowire together with thecharacteristics of a bulk structure. The nanowire can be used in variousproducts such as lasers, transistors, memories, sensors, and othersimilar devices.

Further, there is a recent trend of manufacturing mobile electronicdevices which are downsized and portable, and integrating variousdifferent functions therein. In order to supply electric power to themobile electronic devices, a battery having appropriate capacity isused. However, the capacity of a battery supplying electric power to thedevices may falls behind the function-integrated speed of the devices;that is, the existing battery may be insufficient to rapidly supply theneeded electrical power in an existing mobile electronic device.Therefore, there is a need for a backup battery, and the backup batterymay be required to be developed as wireless chargeable emergency powersource.

SUMMARY

An embodiment provides an apparatus for generating electrical energy byusing applied stresses when light is not applied, and which generateselectrical energy by absorption of light, such as sunlight, and a methodfor manufacturing the apparatus for generating electrical energy.

One embodiment of an apparatus for generating electrical energyincludes; a first electrode, and a second electrode spaced apart fromthe first electrode, and an energy generation layer disposed between thefirst electrode and the second electrode, wherein the energy generationlayer includes a photoelectric conversion layer and piezoelectric layer,and when external force is applied to at least one of the firstelectrode and the second electrode, the piezoelectric layer istransformed to generate electrical energy.

Another aspect of this disclosure provides a method of manufacturing theabove described embodiment of an apparatus for generating electricalenergy.

One embodiment of a method for manufacturing the above embodiment of anapparatus for generating electrical energy includes; disposing a firstelectrode on a substrate, disposing a plurality of nanowires made of apiezoelectric material on the first electrode, forming a photoelectricconversion layer electrically connected to the nanowire on the firstelectrode, and disposing a second electrode on the nanowire and thephotoelectric conversion layer, wherein when an external force isapplied to at least one of the first electrode and the second electrode,the plurality of nanowires may be transformed to generate electricalenergy. In one embodiment the piezoelectric layer may include a singlepiezoelectric nanowire.

In the embodiment where light, such as sunlight, is irradiated, aphotoactive layer absorbs the light to generate electrical energy, andefficient transport of the electrical energy generated using light maybe induced due to a piezoelectric layer adjacent to the photoactivelayer.

In the embodiment wherein light is not irradiated to the apparatus forgenerating electrical energy, electrical energy may be generated byapplying stress to a piezoelectric material layer, thereby transformingthe piezoelectric layer.

The energy generation by sunlight and the energy generation by thepiezoelectric effect may occur simultaneously, and in such anembodiment, the apparatus may have improved energy generation efficiencyand a multifunctional device that simultaneously realizes energygeneration and pressure sensing can be developed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, advantages and features of this disclosurewill become more apparent by describing in further detail embodimentsthereof with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an embodiment of anapparatus for generating electrical energy;

FIG. 2 is an exploded perspective view of the embodiment of an apparatusfor generating electrical energy shown in FIG. 1;

FIG. 3 is a conceptual cross-sectional view showing a first operation ofan embodiment of an apparatus for generating electrical energy;

FIG. 4 is a conceptual cross-sectional view showing a second operationof an embodiment of an apparatus for generating electrical energy;

FIG. 5 is a schematic cross-sectional view of an embodiment of anapparatus for generating electrical energy;

FIG. 6 is an exploded perspective view of the embodiment of an apparatusfor generating electrical energy shown in FIG. 5;

FIG. 7 is a conceptual cross-sectional view showing a first operation ofan embodiment of an apparatus for generating electrical energy;

FIG. 8 is a conceptual cross-sectional view showing a second operationof an embodiment of an apparatus for generating electrical energy;

FIG. 9 is an exploded perspective view of another embodiment of anapparatus for generating electrical energy;

FIG. 10 is an exploded perspective view of another embodiment of anapparatus for generating electrical energy;

FIGS. 11A to 11D are cross-sectional views of steps of an embodiment ofa manufacturing process of an embodiment of an apparatus for generatingelectrical energy;

FIGS. 12A to 12C are graphs showing currents of an embodiment of anapparatus for generating electrical energy;

FIG. 13 is a schematic cross-sectional view of an embodiment of anapparatus for generating electrical energy;

FIG. 14 is a conceptual cross-sectional view showing a first operationof an embodiment of an apparatus for generating electrical energy;

FIG. 15 is a conceptual cross-sectional view showing a second operationof an embodiment of an apparatus for generating electrical energy; and

FIG. 16 is a graph showing currents of an embodiment of an apparatus forgenerating electrical energy.

DETAILED DESCRIPTION

Embodiments now will be described more fully hereinafter with referenceto the accompanying drawings, in which embodiments are shown. Theseembodiments may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the disclosure to thoseskilled in the art. Like reference numerals refer to like elementsthroughout.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may be present therebetween. In contrast, when an element isreferred to as being “directly on” another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the present invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising,” or“includes” and/or “including” when used in this specification, specifythe presence of stated features, regions, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, regions, integers, steps,operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower”, can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Embodiments are described herein with reference to cross sectionillustrations that are schematic illustrations of idealized embodiments.As such, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments should not be construed as limited to theparticular shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from manufacturing. Forexample, a region illustrated or described as flat may, typically, haverough and/or nonlinear features. Moreover, sharp angles that areillustrated may be rounded. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe precise shape of a region and are not intended to limit the scope ofthe disclosure.

All methods described herein can be performed in a suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “suchas”), is intended merely to better illustrate the disclosure and doesnot pose a limitation on the scope thereof unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the embodiments asused herein.

Hereinafter, the embodiments will be described in detail with referenceto the accompanying drawings.

Referring to FIGS. 1 and 2, an embodiment of an apparatus for generatingelectrical energy is described in detail. FIG. 1 is a schematiccross-sectional view of an embodiment of an apparatus for generatingelectrical energy, and FIG. 2 is an exploded perspective view of theembodiment of an apparatus for generating electrical energy shown inFIG. 1.

Referring to FIG. 1 and FIG. 2, an apparatus for generating electricalenergy includes a lower substrate 100 and an upper substrate 200disposed substantially opposite to each other, an energy generationlayer 300 that is disposed between the lower substrate 100 and the uppersubstrate 200, a connection part 401 that electrically connects thelower substrate 100 and the upper substrate 200, and a storage part 402that is connected to the connection part 401. In one embodiment, theenergy generation layer 300 may be formed on the lower substrate 100.

The lower substrate 100 includes a first substrate 110 and a firstelectrode 120 formed on the first substrate 110, and the upper substrate200 includes a second substrate 210 and a second electrode 220 formed onthe second substrate. In one embodiment, the first substrate 110 and thesecond substrate 210 may be flexible and transparent. Although not shownin drawings, in order to facilitate transport of electrons and holes, ablocking layer or a transport layer may be formed on the first electrode120 or the second electrode 220. The blocking layer functions to ensurethat charge carriers of only one type flow in one direction. Forexample, by coating a molybdenum oxide (MoOx) layer on the secondelectrode 220, electron transport may be blocked and hole transport maybe improved, thereby selectively transporting holes to the secondelectrode 220.

Embodiments include configurations wherein the first substrate 110 andthe second substrate 210 may include a flexible material such as plasticso that it may be configured to be transformed external stresses appliedthereto. In one embodiment the first electrode 120 may include indiumtin oxide (“ITO”), carbon nanotubes (“CNT”), a graphene material, atransparent conductive polymer, other materials with similarcharacteristics, or combinations thereof. The second electrode 220 mayinclude gold (Au), an Au-palladium alloy (AuPd), palladium (Pd),platinum (Pt), ruthenium (Ru), and other materials with similarcharacteristics, or combinations thereof. At least one of the firstelectrode 120 and the second electrode 220 may be a flexible electrodeconfigured to be transformed by stresses applied thereto.

The first electrode 120 and the second electrode 220 may be connected toeach other by the connection part 401. Embodiments includeconfigurations wherein the connection part 401 is made of a conductivematerial.

The energy generation layer 300 includes a plurality of piezoelectricnanowires 310 and a photoelectric conversion layer. In one embodimentthe photoelectric conversion layer may be an organic material layer 320that produces electron-hole pairs (excitons) by absorbing light such assunlight, and may include a p-type semiconductor.

The organic material layer 320 may include a p-type semiconductor havingpiezoelectric characteristics. Examples of the p-type semiconductorinclude at least one selected from poly(3-hexylthiophene), polyaniline,polypyrrole, poly(p-phenylene vinylene) (“PPV”), polyvinylene,polyacetylene, polythiophene, combinations thereof and derivativesthereof. In one embodiment the organic material layer 320 may includepoly(2,7-carbazole).

Embodiments of the piezoelectric nanowire 310 may include zinc oxide(ZnO), lead zirconate titanate (PZT), barium titanate (BaTiO₃), aluminumnitride (AlN), gallium nitride (GaN), or silicon carbide (SiC), andother piezoelectric materials with similar characteristics, orcombinations thereof. In the present embodiment, the piezoelectricmaterial making up the piezoelectric nanowire 310 may includesemiconductor characteristics. For example, a piezoelectric nanowire 310made of undoped zinc oxide (ZnO) has n-type semiconductorcharacteristics.

A plurality of piezoelectric nanowires 310 may be grown on the firstelectrode 120. In an embodiment where a plurality of piezoelectricnanowires 310 are grown on the first electrode 120 instead of directlygrown on the first substrate 110, the growth of the piezoelectricnanowires 310 can be easily controlled so that, for example, thepiezoelectric nanowires 310 may be grown in a vertical direction withrespect to the first electrode 120, and uniformity of shapes ordirections between each piezoelectric nanowire 310 may be improved. Inone embodiment, prior to the growth of the nanowire 310, a thin film ofconductive zinc oxide (ZnO) may be grown on the first substrate 110, andin such an embodiment, the zinc oxide thin film which remains afterforming the nanowire 310 may function as a first electrode 120.

The piezoelectric nanowire 310 may extend vertically with respect to thesurface of the first electrode 120 and/or the second electrode 220.Embodiments include configurations wherein the piezoelectric nanowire310 may extend to be inclined in a non-vertical direction with respectto the surface of the first electrode 120 and the second electrode 220.The number of piezoelectric nanowires 310 shown in this embodiment anddrawings are illustrative, and it is clear that the number anddisposition of piezoelectric nanowires 310 may be varied depending on asize and use of the apparatus.

The operation of the apparatus for generating electrical energyaccording to the embodiment shown in FIG. 1 and FIG. 2 will now bedescribed in detail with reference to FIG. 3 and FIG. 4. FIG. 3 is aconceptual cross-sectional view showing an embodiment of a firstoperation of the embodiment of an apparatus for generating electricalenergy, and FIG. 4 is a conceptual cross-sectional view showing anembodiment of a second operation of the embodiment of an apparatus forgenerating electrical energy.

First, referring to FIG. 3, a first operation wherein the apparatus forgenerating electrical energy absorbs light such as sunlight is describedin detail.

If light, such as sunlight, is irradiated to the apparatus forgenerating electrical energy, all of, or only a portion of, theirradiated light may reach the energy generation layer 300. Electronsincluded in the energy generation layer 300 absorb energy from theirradiated light, and then electron-hole pairs (excitons) of an excitedstate may be formed. The electron-hole pairs may be separated intoelectrons 501 and holes 502 at the interface between the p-type organicmaterial layer 320 and the n-type nanowire 310. The separated electrons501 are transported to an anode, i.e., the first electrode 120, alongthe n-type nanowire 310, and the holes 502 are transported to a cathode,i.e., the second electrode 220, along the organic material layer 320.

Although sunlight is shown as being irradiated from the bottom of theapparatus for generating electrical energy in the illustratedembodiment, sunlight may also or alternatively be irradiated from thetop of the apparatus. In the embodiment where sunlight is irradiatedfrom the top of the apparatus for generating electrical energy, aplurality of piezoelectric nanowires 310 may induce a light-harvestingeffect for the irradiated light in order to improve electrical energygeneration efficiency of the energy generation layer 300.

As the electrons 501 are transported to the first electrode 120 and theholes 502 are transported to the second electrode 220 as explainedabove, a current may flow through a closed circuit consisting of thefirst electrode 120 and the second electrode 220 connected to each otherby the connection part 401, and the energy generation layer 300. Thestorage part 402 may be electrically connected to the connection part401 so that electrical energy generated by the energy generation layer300 may be stored therein.

In one embodiment, the storage part 402 may include a chargeablebattery, a capacitor, or other electrical energy storage devices.Embodiments of the battery may include a nickel-cadmium battery, anickel-hydrogen battery, a lithium ion battery, a lithium polymerbattery, and other similar batteries. The storage part 402 may furtherinclude an amplifier (not shown) for amplifying a voltage.

Next, referring to FIG. 4, a second operation wherein stress is appliedto the apparatus for generating electrical energy is described indetail.

If stress is applied to the apparatus for generating electrical energy,the second substrate 210 and the second electrode 220 may bend down at aposition where stress is applied A (also referred to as a“stress-applied position” A). As the second substrate 210 and the secondelectrode 220 bend down, the distance between the first electrode 120and the second electrode 220 decreases, and thus piezoelectric nanowires310 disposed at the position A may be compressed and physicallytransformed, and the transformed piezoelectric nanowires 310 exhibit apiezoelectric effect. Thus, each portion of the piezoelectric nanowires310 has a predetermined electrical potential due to the appliedcompressive stress or tensile stress.

Electrons 503 generated by the piezoelectric effect of the piezoelectricnanowires 310 are transported to the first electrode 120, e.g., alongthe nanowires 310, thus generating electrical energy.

At this time, the electrical energy generated by the piezoelectricnanowires 310 may be stored in the storage part 402.

Although FIG. 4 illustrates a case wherein stress is applied to the topof the apparatus for generating electrical energy to bend the secondsubstrate 210 and the second electrode 220, the same effect may beobtained by applying stress to the first electrode 120 or both of thefirst electrode 120 and the second electrode 220 simultaneously. Thus,electrical energy may be generated by pressing or bending the apparatusfor generating electrical energy.

As explained, the apparatus for generating electrical energy maygenerate electrical energy by a piezoelectric phenomenon by applyingstress to the piezoelectric nanowires 310, as well as using light suchas sunlight.

Referring to FIG. 5 and FIG. 6, another embodiment of an apparatus forgenerating electrical energy is described in detail. FIG. 5 is aschematic cross-sectional view of another embodiment of an apparatus forgenerating electrical energy, and FIG. 6 is an exploded perspective viewof the embodiment of an apparatus for generating electrical energy shownin FIG. 5.

Referring to FIG. 5 and FIG. 6, an embodiment of an apparatus forgenerating electrical energy is similar to the embodiment as shown inFIG. 1 and FIG. 2. Specifically, the apparatus for generating electricalenergy includes a lower substrate 100 and an upper substrate 200disposed substantially opposite to each other, an energy generationlayer 300 that is disposed between the lower substrate 100 and the uppersubstrate 200, a connection part 401 that electrically connects thelower substrate 100 and the upper substrate 200, and a storage part 402that is connected to the connection part 401. The energy generationlayer 300 may be formed on the lower substrate 100.

The lower substrate 100 includes a first substrate 110 and a firstelectrode 120 that is formed on the first substrate 110, and the uppersubstrate 200 includes a second substrate 210 and a second electrode 220that is formed on the second substrate. In one embodiment the firstsubstrate 110 and the second substrate 210 may be flexible andtransparent. Although not shown, a blocking layer or a transport layermay be further disposed on the first electrode 120 and the secondelectrode 220 in order to facilitate transport of electrons and holes inone direction, as described above. The first electrode 120 and thesecond electrode 220 are connected to each other by a connection part401. In the present embodiment, the connection part 401 is made of aconductive material.

The energy generation layer 300 includes a plurality of piezoelectricnanowires 310 and a photoelectric conversion layer.

Contrary to the previous embodiment, the photoelectric conversion layerof the present embodiment of an apparatus for generating electricalenergy further includes an organic material layer 320 that produceselectron-hole pairs (excitons) by absorbing light, such as sunlight, andan inorganic material layer 330 that is distributed in the organicmaterial layer 320.

The organic material layer 320 and the inorganic material layer 330 aremixed between the first electrode 120 and the second electrode 220. Inone embodiment, the mixing is not entirely homogenous, rather theinorganic material layer 330 tends to form lobes of material within theorganic material layer 320. In one embodiment, the organic materiallayer 320 may include a p-type organic semiconductor, and the inorganicmaterial layer 330 may be an n-type semiconductor.

The organic material layer 320 may include a semiconductor havingpiezoelectric characteristics such as poly(3-hexylthiophene) (“P3HT”),polyaniline, polypyrrole, poly(p-phenylene vinylene) (“PPV”),polyvinylene, polyacetylene, polythiophene, combinations thereof andderivatives thereof. In one embodiment, the organic material layer 320may include poly(2,7-carbazole).

In one embodiment, the inorganic material layer 330 may include at leastone of phenyl-C61-butyric acid methyl ester (“PCBM”), phenyl-C71-butyricacid methyl ester (PC₇₁BM), and other materials with similarcharacteristics.

The piezoelectric nanowire 310 may include zinc oxide (ZnO), leadzirconate titanate (PZT), barium titanate (BaTiO₃), aluminum nitride(AlN), gallium nitride (GaN), silicon carbide (SiC), and anotherpiezoelectric material, or combinations thereof.

In one embodiment, a plurality of piezoelectric nanowires 310 may begrown on the first electrode 120.

The piezoelectric nanowires 310 may extend in a vertical direction withrespect to a surface of the first electrode 120 and the second electrode220, e.g., in a direction substantially perpendicular to both thesurface of the first electrode 120 and a surface of the second electrode220. The piezoelectric nanowires 310 may extend to be inclined in anon-vertical direction with respect to the surface of the firstelectrode 120 and the second electrode 220, e.g., the piezoelectricnanowires 310 may extend to be substantially oblique to the surface ofthe first electrode 120 and the second electrode 220. The number ofpiezoelectric nanowires 310 shown in the present embodiment and drawingsis illustrative, and it is clear that the number and disposition of thepiezoelectric nanowires 310 may be varied depending on the size and useof the apparatus.

Operation of the apparatus for generating electrical energy will now bedescribed in detail with reference to FIGS. 7 and 8. FIG. 7 is aconceptual cross-sectional view showing an embodiment of a firstoperation of the embodiment of an apparatus for generating electricalenergy, and FIG. 8 is a conceptual cross-sectional view showing anembodiment of a second operation of an embodiment of the apparatus forgenerating electrical energy.

First, referring to FIG. 7, a first operation wherein the apparatus forgenerating electrical energy absorbs light, such as sunlight, isdescribed in detail.

If light, such as sunlight, is irradiated to the apparatus forgenerating electrical energy, and electrons included in the energygeneration layer 300 absorb energy from the irradiated light,electron-hole pairs (excitons) of an excited state may be formed. Theelectron-hole pairs may be separated into electrons 501 and holes 502 atthe interface between the p-type organic material layer 320 and then-type inorganic material layer 330, respectively. The separatedelectrons 501 are transported to an anode, which in the presentembodiment is the first electrode 120, along the n-type inorganicmaterial layer 330, and the holes 502 are transported to a cathode,which in the present embodiment is the second electrode 220, along theorganic material layer 320.

The electrons 501 are transported by hopping between the n-typeinorganic material layers 330 that are spaced apart from each other, andthe separated electrons 501 and holes 502 may be recombined and lostduring the hopping between the separated inorganic material layers 330.Since the inorganic material layer 330 of the present embodiment of anapparatus for generating electrical energy contacts a plurality of thepiezoelectric nanowires 310, the piezoelectric nanowires 310 connect theinorganic material layers 330 that are spaced apart from each other, andthus electrons 501 may be easily transported to the first electrode 120through the piezoelectric nanowires 310. Thus, the piezoelectricnanowire 310 may function as a transport layer for the electrons 501.

As explained above, since the photoelectric conversion layer of theenergy generation layer of the present embodiment of an apparatus forgenerating electrical energy further includes an inorganic materiallayer 330 that is distributed in an organic material layer 320, theefficiency of separating electron-hole pairs produced in the organicmaterial layer 320 may be improved and electron transport may befacilitated.

Thus, as electrons 501 are transported to the first electrode 120 andholes 502 are transported to the second electrode 220, current may flowthrough a closed circuit consisting of the first electrode 120 and thesecond electrode 220 that are connected to each other by the connectionpart 401, and an energy generation layer 300. The storage part 402 maybe electrically connected to the connection part 401 so that electricalenergy produced by the energy generation layer 300 may be stored in thestorage part 402.

Next, referring to FIG. 8, a second operation wherein stress is appliedto the embodiment of an apparatus for generating electrical energy isdescribed in detail.

If stress is applied to the present embodiment of an apparatus forgenerating electrical energy, the second substrate 210 and the secondelectrode 220 may bend down at a position where stress is applied B(also referred to as “a stress-applied position” B). As the secondsubstrate 210 and the second electrode 220 are bent down, the distancebetween the first electrode 120 and the second electrode 220 decreasesand thus piezoelectric nanowires 310 disposed at the position (B) may becompressed and physically transformed. The transformed piezoelectricnanowires 310 exhibit the piezoelectric effect, and electrons 503generated by piezoelectric effects on the piezoelectric nanowires 310are transported to the first electrode 120 thus generating electricalenergy. Electrical energy produced by the nanowires 310 may be stored inthe storage part 402.

Although FIG. 8 illustrates an embodiment wherein stress is applied tothe top of the apparatus for generating electrical energy to bend thesecond substrate 210 and the second electrode 220, the same effects maybe obtained by applying stress to the first electrode 120 and/or both ofthe first electrode 120 and the second electrode 220. Thus, electricalenergy may be generated by pressing or bending the apparatus forgenerating electrical energy.

As explained above, the apparatus for generating electrical energy maygenerate electrical energy by the piezoelectric phenomenon by applyingstress to the nanowires 310, as well as by using light, such assunlight.

The photoelectric conversion layer of the energy generation layer 300 ofthe present embodiment of an apparatus for generating electrical energyfurther includes the inorganic material layer 330 that is distributed inthe organic material layer 320 and electrons produced in thephotoelectric conversion layer are transported to an anode through theinorganic material layer 330, and the piezoelectric nanowires 310 mayfunction as a transport layer for electrons 501. Therefore, energygeneration efficiency of the photoelectric conversion layer may beimproved.

Many features of the embodiments of the apparatus for generatingelectrical energy as shown in FIG. 1 to FIG. 4 may be applied to theapparatus for generating electrical energy as shown in FIG. 5 to FIG. 8.

Next, referring to FIG. 9, another embodiment of an apparatus forgenerating electrical energy is described in detail. FIG. 9 is anexploded perspective view of the embodiment of an apparatus forgenerating electrical energy.

The embodiment of an apparatus for generating electrical energy shown inFIG. 9 is similar to the embodiments of an apparatus shown in FIG. 2 orFIG. 6. The constructions and functions of the first substrate 110, thesecond substrate 210, and the energy generation layer 300 of theembodiment of an apparatus for generating electrical energy as shown inFIG. 9 are similar to those shown in FIG. 2 or FIG. 6, and thereforedetailed descriptions are omitted.

However, contrary to the previously described embodiments of apparatusfor generating electrical energy shown in FIG. 2 or FIG. 6, the secondelectrode 220 of the apparatus for generating electrical energy shown inFIG. 9 has a wave-shaped structure due to a plurality of recess portions(A1) and convex additions (A2), and thus the surface thereof may not beflat, i.e., it is uneven. As such, in the embodiment where the surfaceof the second electrode 220 is uneven, a contact area between the secondelectrode 220 and an organic material layer may be increased to improvetransport of electrical energy produced by sunlight, thereby improvingenergy efficiency. That is, the uneven surface of the second electrode220 increases the surface area thereof.

Many features of the embodiments of apparatus for generating electricalenergy shown in FIG. 2 or FIG. 6 may be applied to the embodiment of anapparatus shown in FIG. 9.

Next, referring to FIG. 10, another embodiment of an apparatus forgenerating electrical energy is described in detail. FIG. 10 is anexploded perspective view of the additional embodiment of an apparatusfor generating electrical energy.

The embodiment of an apparatus for generating electrical energy shown inFIG. 10 is similar to the apparatus for generating electrical energyshown in FIG. 2 or FIG. 6. Particularly, the constructions and functionsof the first substrate 110, the second substrate 210, and the energygeneration layer 300 of the present embodiment of an apparatus forgenerating electrical energy shown in FIG. 10 are similar to those shownin FIG. 2 or FIG. 6, and therefore detailed explanations are omitted.

However, contrary to the previously described embodiments of apparatusfor generating electrical energy shown in FIG. 2 or FIG. 6, the firstelectrode 120 and the second electrode 220 of the present embodiment ofan apparatus for generating electrical energy shown in FIG. 10 consistof a plurality of sub-electrodes. The first electrode 120 includes aplurality of first sub-electrodes 120 a, 120 b, and 120 c that extend ina first direction (D2) and are spaced apart from each other on the firstsubstrate 110. The second electrode 220 includes a plurality of secondsub-electrodes 220 a, 220 b, and 220 c that extend in a second direction(D3) that is substantially perpendicular to the first direction (D2),and are spaced apart from each other on the second substrate 210.

The first electrode 120 and the second electrode 220 respectivelyincluding a plurality of first sub-electrodes 120 a, 120 b, and 120 cand second sub-electrodes 220 a, 220 b, and 220 c may have a matrixarray format. The number of first electrodes 120 and second electrodes220 shown in FIG. 10 is illustrative, and it is not limited thereto andmay be varied depending upon the size and use of the apparatus.

A stress-applied position, i.e., a position where a stress is applied,may be sensed by sensing an electrode through which current flows amonga plurality of the first electrodes 120 a, 120 b, and 120 c and anelectrode through which current flows among a plurality of the secondelectrodes 220 a, 220 b, and 220 c when using an apparatus forgenerating electrical energy including a first electrode 120 and asecond electrode 220 disposed in a matrix array format. Therefore, ifthe apparatus for generating electrical energy is used as a touchsensor, etc., the position where a stress is applied may be sensed.Further, a multifunctional device that is capable of simultaneouslyrealizing energy generation and pressure sensing may be provided.

Although piezoelectric nanowires 310 are formed on a plurality of thefirst electrodes 120 in the embodiment of an apparatus for generatingelectrical energy shown in FIG. 10, piezoelectric nanowires 310 may beformed on the regions where the first electrode 120 and the secondelectrode 220 cross each other in an another embodiment of an apparatusfor generating electrical energy.

Further, although the first electrodes 120 and the second electrodes 220extend in perpendicular directions with respect to each other in theembodiment of an apparatus for generating electrical energy shown inFIG. 10, the second electrodes 220 may extend in an inclined, e.g.,oblique, direction with respect to the first direction (D2) in which thefirst electrodes 120 extend in an alternative embodiment of an apparatusfor generating electrical energy.

In addition, although the surface of the second electrode 220 is flat inthe embodiment of an apparatus for generating electrical energy shown inFIG. 10, a recess portion and a convex addition may be formed on thesurface of the second electrode 220 such that the surface of the secondelectrode 220 may be uneven, as in the previously described embodimentof an apparatus for generating electrical energy shown in FIG. 9.

Many features of the embodiment of an apparatus for generatingelectrical energy shown in FIG. 2 or FIG. 6 may also be applied to theapparatus for generating electrical energy shown in FIG. 10.

As explained, the present embodiment of an apparatus for generatingelectrical energy may generate electrical energy by absorbing irradiatedlight or using applied stress. Additionally, since a touch sensor thatis capable of sensing the stress-applied position may be realized byforming at least one of the first electrode 120 and the second electrode220 in an array format in an apparatus for generating electrical energy,the apparatus may be used in an electronic device for sensing stresssuch as a touch sensor. Further, the apparatus for generating electricalenergy may be used for a display device such as a touch panel, a touchscreen, or other display devices, as well as other sensing applications,e.g., robot skin, etc. If a plurality of apparatuses for generatingelectrical energy are electrically connected in an array format,electrical energy produced in each apparatus may be amplified.

Now, referring to FIG. 11A to FIG. 11D, an embodiment of a method formanufacturing an embodiment of an apparatus for generating electricalenergy is described in detail. FIGS. 11A to 11D are cross-sectionalviews of steps of an embodiment of a manufacturing process of anembodiment of an apparatus for generating electrical energy.

Referring to FIG. 11A, a first electrode 120 is formed on a firstsubstrate 110. As described above, the first substrate 110 and the firstelectrode 120 may be bent by applied stress, and they may be made of atransparent material. The first electrode 120 is made of a conductivematerial, and embodiments include configurations wherein it may beformed by plating, sputtering, electron beam deposition, thermaldeposition, or other similar methods. For example, the first electrode120 may include indium tin oxide (“ITO”), sapphire, gallium nitride(GaN), silicon carbide (SiC), zinc oxide (ZnO), carbon nanotubes(“CNT”), a conductive polymer, nanofibers, a nanocomposite material,combinations thereof and other materials with similar characteristics.The first electrode 120 may include a gold-palladium alloy (AuPd), gold(Au), palladium (Pd), platinum (Pt), or ruthenium (Ru).

The first electrode 120 may function as a lower electrode for supportingpiezoelectric nanowires to be formed thereon as described below.

Referring to FIG. 11B, a nanomaterial layer 30 may then be formed on thefirst electrode 120. In one embodiment, the nanomaterial layer 30 may bethinly formed on the first electrode 120 by spin coating, dip coating,an evaporation method or other similar methods. As an example, in oneembodiment the thickness of the nanomaterial layer 30 may be about 3 nmto about 50 nm. According to another embodiment, the nanomaterial layer30 may be made of zinc acetate.

As shown in FIG. 11C, nanowires 310 can be grown by introducing thesubstrate 110 having the nanomaterial layer 30 formed thereon to asolution in which the nanomaterial is dissolved. The nanowires 310 mayhave piezoelectric characteristics, and may include zinc oxide (ZnO),lead zirconate titanate (PZT), barium titanate (BaTiO₃), aluminumnitride (AlN), gallium nitride (GaN), silicon carbide (SiC), otherpiezoelectric materials with similar characteristics, or combinationsthereof.

Next, referring to FIG. 11D, a photoelectric conversion layer may beformed on the first electrode 120 having nanowires 310 formed thereon.In the present embodiment, the photoelectric conversion layer mayinclude an organic material layer 320 and an inorganic material layer330 that is distributed in the organic material layer 320, and theorganic material layer 320 may include a p-type organic semiconductorand the inorganic material layer 330 may be an n-type inorganicsemiconductor. Alternative embodiments include configurations whereinthe photoelectric conversion layer may consist of only the organicmaterial layer 320.

Next, the first electrode 120 and the second electrode 220 are disposedto be substantially opposite to each other with an energy generationlayer 300 disposed therebetween. In addition, the first electrode 120and the second electrode 220 are connected to each other by a connectionpart 401 to form an apparatus for generating electrical energy. Astorage part 402 may be electrically connected to the connection part401.

Referring to FIGS. 12A to 12C, an experimental example is hereinafterdescribed. FIGS. 12A to 12C are graphs showing currents of variousembodiments of an apparatus for generating electrical energy. In theexperimental example, polyethersulfone (“PES”) is used as a substrate,and ITO coated on the PES is used as a lower electrode. Zinc oxide (ZnO)piezoelectric nanowires are grown on the ITO lower electrode, and then aP3HT/PCBM organic/inorganic blend was coated thereon. A molybdenum oxide(MoO_(x)) layer is coated on the P3HT/PCBM organic/inorganic blend inorder to block electron transport to an upper electrode, and then an Aulayer was coated on the upper substrate as an upper electrode to form anapparatus for generating electrical energy.

FIG. 12A is a graph showing peaks of current generated when theapparatus for generating electrical energy used in the experimentalexample is pressed or bent using an instrument. Referring to FIG. 12A,it can be seen that energy is generated by the piezoelectric effectwithin the apparatus for generating electrical energy.

FIG. 12B is a graph showing current generated in the apparatus forgenerating electrical energy used in the experimental example under roomlighting conditions. Referring to FIG. 12B, it can be seen that currentflows when measured under room lighting conditions, indicating thatenergy is generated by the solar cell effect in a photoelectricconversion layer.

FIG. 12C is a graph showing current generated when an external force isapplied to the apparatus for generating electrical energy used in theexperimental example while current is generated in the apparatus underroom lighting conditions. That is, while the previous two graphs ofFIGS. 12A and 12B illustrated electrical energy production underpressure application conditions and room lighting conditions,respectively, the present graph of 12C illustrates electrical energyproduction under pressure application conditions and room lightingconditions. Referring to FIG. 12C, it can be seen that in the apparatusfor generating electrical energy, energy is generated by the solar celland additional current is also generated by the piezoelectric effectwhen external force is applied, so the apparatus can be simultaneouslyoperated by the solar cell effect and the piezoelectric effect.

Referring to FIG. 13, another embodiment of an apparatus for generatingelectrical energy is described in detail. FIG. 13 is a schematiccross-sectional view of another embodiment of an apparatus forgenerating electrical energy.

Referring to FIG. 13, the present embodiment of an apparatus forgenerating electrical energy is similar to the previously describedembodiment of an apparatus for generating electrical energy illustratedin FIGS. 1 and 2. The apparatus for generating electrical energyincludes a lower substrate 100 and an upper substrate 200 disposedsubstantially opposite to each other, an energy generation layer 300that is disposed between the lower substrate 100 and the upper substrate200, a connection part 401 that electrically connects the lowersubstrate 100 and the upper substrate 200, and a storage part 402 thatis connected to the connection part 401.

The lower substrate 100 includes a first substrate 110 and a firstelectrode 120 formed on the first substrate 110, and the upper substrate200 includes a second substrate 210 and a second electrode 220 formed onthe second substrate. In the present embodiment, the first substrate 110and the second substrate 210 may be flexible and transparent. The firstsubstrate 110 and the second substrate 210 may include a flexiblematerial such as plastic so that it may be transformed by externallyapplied stresses. The first electrode 120 may include ITO, CNT, agraphene material, a transparent conductive polymer, and other similarmaterials, or combinations thereof. The second electrode 220 may includegold (Au), an Au-palladium alloy (AuPd), palladium (Pd), platinum (Pt),ruthenium (Ru), and other similar materials, or combinations thereof. Atleast one of the first electrode 120 and the second electrode 220 may bea flexible electrode that is transformed by stresses applied thereto.

Although not shown in drawings, as described above in order tofacilitate transport of electrons and holes in one direction, a blockinglayer or a transport layer may be formed on the first electrode 120 orthe second electrode 220 or both. For example, by coating a molybdenumoxide (MoOx) layer on the second electrode 220, electron transport maybe blocked and hole transport may be improved, thereby selectivelytransporting holes to the second electrode 220.

The first electrode 120 and the second electrode 220 may be connected toeach other by the connection part 401. In the present embodiment, theconnection part 401 is made of a conductive material.

The energy generation layer 300 includes the piezoelectric layer 301 andan organic material layer 320.

The piezoelectric layer 301 may include zinc oxide (ZnO), lead zirconatetitanate (PZT), barium titanate (BaTiO₃), aluminum nitride (AlN),gallium nitride (GaN), or silicon carbide (SiC), and other piezoelectricmaterials with similar characteristics, or combinations thereof. In thepresent embodiment, the piezoelectric material making up thepiezoelectric layer 301 may include semiconductor characteristics. Forexample, in one embodiment, a piezoelectric layer 301 made of undopedzinc oxide (ZnO) has n-type semiconductor characteristics.

The present embodiment of an apparatus for generating electrical energyincludes a thin planer-shaped piezoelectric layer 301 unlike thenanowire-shaped piezoelectric material that has been described in detailabove.

The organic material layer 320 may include a p-type organicsemiconductor as a photoelectric conversion layer that produceselectron-hole pairs (excitons) by absorbing light, such as sunlight. Theorganic material layer 320 includes a p-type semiconductor havingpiezoelectric characteristics. The organic material layer 320 includesat least one material having piezoelectric characteristics selected frompoly(3-hexylthiophene), polyaniline, polypyrrole, poly(p-phenylenevinylene) (PPV), polyvinylene, polyacetylene, polythiophene, othermaterials with similar characteristics and derivatives thereof. In oneparticular embodiment, the organic material layer 320 may includepoly(2,7-carbazole). Although not shown, the energy generation layer 300may further include an inorganic material layer, and the inorganicmaterial layer may include a n-type semiconductor.

Operation of the present embodiment of an apparatus for generatingelectrical energy illustrated in FIG. 13 will now be described in detailwith reference to FIGS. 14 and 15. FIG. 14 is a conceptualcross-sectional view showing a first operation of the present embodimentof an apparatus for generating electrical energy, and FIG. 15 is aconceptual cross-sectional view showing a second operation of theapparatus for generating electrical energy.

First, referring to FIG. 14, a first operation wherein the apparatus forgenerating electrical energy absorbs light, such as sunlight, isdescribed in detail.

If light, such as sunlight, is irradiated to the apparatus forgenerating electrical energy, an entirety or a portion of the irradiatedlight may reach the energy generation layer 300. Electrons included inthe energy generation layer 300 absorb energy from the irradiated light,and then electron-hole pairs (excitons) of an excited state may beformed. The electron-hole pairs may be separated into electrons 501 andholes 502 at the interface between the p-type organic material layer 320and the n-type nanowire 301. The separated electrons 501 are transportedto an anode, which in the present embodiment is the first electrode 120,along the n-type nanowire 301, and the holes 502 are transported to acathode, which in the present embodiment is the second electrode 220,along the organic material layer 320.

Although sunlight is irradiated from the bottom of the apparatus forgenerating electrical energy in the embodiment as shown, it may beirradiated from the top of the apparatus.

As the electrons 501 are transported to the first electrode 120 and theholes 502 are transported to the second electrode 220 as explainedabove, a current may flow through a closed circuit consisting of thefirst electrode 120 and the second electrode 220 connected to each otherby the connection part 401, and the energy generation layer 300. Thestorage part 402 may be electrically connected to the connection part401 so that electrical energy generated by the energy generation layer300 may be stored therein.

The storage part 402 may include a chargeable battery, a capacitor, oranother electrical energy storage device as described above, and thebattery refers to, as examples, a nickel-cadmium battery, anickel-hydrogen battery, a lithium ion battery, a lithium polymerbattery and various other batteries with similar characteristics, asdescribed above. The storage part 402 may further include an amplifier(not shown) for amplifying voltage.

Next, referring to FIG. 15, a second operation wherein stress is appliedto the present embodiment of an apparatus for generating electricalenergy is described in detail.

If stress is applied to the present embodiment of an apparatus forgenerating electrical energy, the apparatus for generating electricalenergy may bend in a downward direction. As the second substrate 210 andthe second electrode 220 bend down, the piezoelectric layer 301 may becompressed and physically transformed, and the transformed piezoelectriclayer 301 exhibits a piezoelectric effect. Thus, each portion of thepiezoelectric layer 301 has a predetermined potential due to the appliedcompressive stress or tensile stress.

Electrons 503 generated by the piezoelectric effect of the piezoelectriclayer 301 are transported to the first electrode 120, thus generatingelectrical energy.

At this time, the electrical energy generated by the piezoelectric layer301 may be stored in the storage part 402.

Although FIG. 15 illustrates an embodiment wherein stress is applied toboth of the first electrode 120 and the second electrode 220, the sameeffect may be obtained by applying stress to only the top or bottom ofthe apparatus for generating electrical energy or one side of theapparatus for generating electrical energy. Thus, electrical energy maybe generated by pressing or bending the present embodiment of anapparatus for generating electrical energy.

As explained, the present embodiment of an apparatus for generatingelectrical energy may generate electrical energy by a piezoelectricphenomenon by applying stress to the piezoelectric layer, as well asusing light such as sunlight.

Referring to FIG. 16, an experimental example is hereinafter described.FIG. 16 is a graph showing current generated in the present embodimentof an apparatus for generating electrical energy. In the experimentalexample, PES is used as a substrate, and ITO coated on the PES is usedas an electrode. A piezoelectric thin layer of zinc oxide (ZnO) islaminated on the ITO electrode, and then a P3HT/PCBM organic/inorganicblend is coated thereon. A molybdenum oxide (MoO_(x)) layer is coated onthe P3HT/PCBM organic/inorganic blend in order to block electrontransport to an upper electrode, and then a Au layer was coated as anupper electrode to form an apparatus for generating electrical energy.

The present embodiment of an apparatus for generating electrical energyused in the present Experimental Example was placed under room light,and the apparatus for generating electrical energy was pressed or bent.Peaks of the generated voltages are illustrated in FIG. 16.

Referring to FIG. 16, the apparatus for generating electrical energygenerates a first voltage (E1) measured under room light, indicatingthat energy was generated by the solar cell effect in a photoelectricconversion layer. When a stress is applied to the apparatus forgenerating electrical energy, a second voltage (E2) was generated,indicating that energy was generated by piezoelectric effects of theapparatus for generating electrical energy.

While this disclosure has been described in connection with what ispresently considered to be practical embodiments, it is to be understoodthat the invention is not limited to the disclosed embodiments, but, onthe contrary, is intended to cover various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims.

1. A method for manufacturing an apparatus for generating electrical energy, the method comprising: disposing a first electrode on a substrate, disposing a nanowire comprising a piezoelectric material on the first electrode, disposing a photoelectric conversion layer which is electrically connected to the nanowire on the first electrode, and disposing a second electrode on the nanowire and the photoelectric conversion layer, wherein when an external force is applied to at least one of the first electrode and the second electrode, the nanowire is transformed to generate electrical energy.
 2. The method of claim 1, wherein at least one of the first electrode and the second electrode is configured to be transformed by stresses applied thereto.
 3. The method of claim 18, wherein the substrate is configured to be transformed by stresses applied thereto.
 4. The method of claim 1, wherein at least one of the first electrode and the second electrode comprises a transparent material.
 5. The method of claim 4, wherein the substrate comprises a transparent material.
 6. The method of claim 1, wherein the step of disposing nanowire comprising a piezoelectric material on the first electrode comprises: disposing a nanomaterial layer on the first electrode, and forming the nanowire from the nanomaterial layer. 